Single-phase and three-phase motors are used in various applications. A single-phase motor may be comprised of a stator having a main and auxiliary winding and a rotor having electrical conductors formed in it. An electrical current is selectively provided through the windings to induce a secondary current in the rotor. The rotating magnetic field generated by the currents in the windings and rotor conductors rotate the rotor to generate torque on the output shaft of the rotor. A three-phase motor has three stator windings that are displaced by 120 degrees. In response to current phases flowing in the windings, an air gap flux induces current in the rotor conductors and generates torque on the rotor output shaft. The windings may be powered directly from an AC source or a DC inverter may be used to supply power at a required frequency and amplitude for a selected speed.
The stator windings are typically an insulated electrical conductor. Most commonly the stator has a slot structure in which the conductor is wrapped multiple times to form a winding. The gauge of the wire and the number of turns affect the output and efficiency of the motor. The slot in which the wire is wrapped is typically sized to accommodate a particular gauge wire for a predetermined number of turns. In motor manufacture, stators may be manufactured in large numbers for installation in electrical motors. One component of cost for a stator is the type of conductor used for the windings. Copper is frequently used, but as the cost of copper has increased significantly, the use of cheaper aluminum has grown. A problem with substituting aluminum for copper arises from the greater resistivity present in an aluminum wire in comparison with a copper wire of the same gauge. Consequently, the gauge of an aluminum wire needs to be larger in order for the aluminum wire to carry a current roughly the same magnitude as the copper wire being replaced. Unfortunately, the stator gap is typically too small to accommodate the number of turns of the larger aluminum wire. If the stator must be re-designed or modified to accept the larger gauge aluminum wire, then any savings from substituting aluminum for copper in a winding is virtually eliminated.